The Applicant has developed a range of Memjet® inkjet printers as described in, for example, WO2011/143700, WO2011/143699 and WO2009/089567, the contents of which are herein incorporated by reference. Memjet® printers employ a stationary printhead in combination with a feed mechanism which feeds print media past the printhead in a single pass. Memjet® printers therefore provide much higher printing speeds than conventional scanning inkjet printers.
High-speed, single-pass inkjet printing requires accurate media handling, especially in the print zone of the printhead, in order to provide acceptable print quality. With fixed printheads of a given length, relatively wide print zones may be constructed by arranging printheads in a staggered overlapping array across the print zone. For example, an A3 print zone may be constructed by positioning a pair of A4 printheads in a staggered overlapping arrangement.
For relatively narrow print zones (e.g. A4 size or narrower), a system of entry and exit rollers in combination with a fixed media platen generally provides sufficient stability in the print zone for acceptable print quality (see, for example, U.S. Pat. No. 8,523,316, the contents of which are herein incorporated by reference).
However, for wider media widths and/or faster print speeds, more complex media feed mechanisms are usually required. For example, U.S. Pat. No. 8,540,361 describes a feed mechanism suitable for wideformat printing comprising a combination of a fixed vacuum platen, an upstream drive roller and a downstream vacuum belt mechanism. The printer described in U.S. Pat. No. 8,540,361 employs five printhead modules arranged in a staggered overlapping array across the print zone.
In other high-speed printers, vacuum belt mechanisms may be employed. However, vacuum belt mechanisms, which transport media through the print zone, are problematic for inkjet printing, because the belt may become fouled with ink during printing. Moreover, inkjet printheads typically perform a number of inter-page spits so as to reduce the frequency of maintenance interventions and endless belts are not amenable to inter-page spitting due to ink fouling.
It would be desirable to provide a printer having a feed mechanism suitable for feeding sheets of print media through print zones defined by a plurality of overlapping printheads.